The present invention relates to broadcast spreaders for seeds and granular materials, and in particular, to a device for shifting the spread pattern of a broadcast spreader to provide an even distribution of seeds or material to accommodate various speeds of operation, material densities, and material granular sizes.
Broadcast spreaders are generally known for dispersing seeds or other granular material from a hopper. Typically, such material is metered through an aperture in the hopper onto a rotating impeller and cast therefrom in a pattern. Some spreaders are hand-held and operated. Typically, they are wheelmounted, and the impeller rotates at a rate related to the speed at which the spreader moves by interconnection to a wheel or axle of the spreader.
While effective in dispersing materials, broadcast spreaders have long been known to provide uneven sowing, and maintenance of an even spread pattern has long been sought. The distribution of material from a broadcast spreader is affected by the position and rate at which material is placed on the impeller, the rate of impeller rotation, and the type of material distributed.
For example, where impellers are driven by interconnection with a wheel or axle of the spreader, the rate of impeller rotation varies with the speed at which the spreader moves. Such broadcast spreaders are typically designed to provide an even spread pattern when moving at an optimum design speed. When individual walking speeds vary from the design speed, the impeller rate changes, and the spread pattern shifts to one side or another. The position and rate at which material is placed on the impeller also affect the location of the spread pattern, so that the shape and position of the feed opening to the impeller may vary the spread pattern. Even application of material and proper orientation of the spread pattern have, consequently, been the subject of numerous developments.
Rittenhouse, U.S. Pat. No. 1,058,103, discloses a handseeder having a peculiarly shaped feed opening and controlling slide for evenly sowing seeds of different sizes at different feed rates. Sherer, U.S. Pat. No. 2,941,811 discloses another such feed opening on a wheel-mounted spreader The feed opening is shaped to provide a uniform distribution of material despite the density of application or speed at which the spreader moves. Doering, U.S. Pat. No. 4,548,362, further discloses a metering apparatus for separately controlling the spread pattern and the flow rate of a broadcast spreader by cooperatively adjusting openings in rotatable plates at the feed opening of the hopper.
Broadcast spreaders are extremely effective in dispersing particulate materials. However, lighter materials have different spread patterns than heavier materials in the same spreader.
Thus, the need exists to provide adjustments which enable versatility in use of spreaders. Moreover, further improvements continue to be sought to provide even distribution and consistent spread patterns.